Biaxial strain and variable stiffness in aponeuroses
Biaxial strain and variable stiffness in aponeuroses
复制标题
DOI：
10.1113/jphysiol.2009.173690
复制
发表时间：
2009-09-01
影响因子：
5.5
通讯作者：
Roberts, Thomas J.
中科院分区：
文献类型：
--
作者：
Azizi, Emanuel;Roberts, Thomas J.
许多肌肉的弹性结构包括肌外游离肌腱和片状腱膜。腱膜的一个重要区别特征是这些腱结构充当肌束的附着和插入表面，因此围绕肌腹的大部分。因此，当收缩肌肉凸出以保持恒定体积时，腱膜必须平行（纵向）和垂直（横向）于肌肉的作用线扩张。在这项研究中，我们使用双平面高速透视来跟踪火鸡腓肠肌外侧腱膜在原位产生主动和被动力期间的应变模式。我们发现，在被动力产生过程中，腱膜的行为与单轴载荷一致，因为腱膜仅在纵向上拉伸。相比之下，我们的结果表明，在主动力产生过程中，腱膜在纵向和横向上都被拉伸，并且横向应变平均比纵向应变大 4 倍。腱膜的双轴加载似乎可以有效地调节纵向刚度，因为我们发现纵向测量的刚度与横向应变成比例变化。我们得出的结论是，主动力产生过程中的双轴应变将腱膜与自由肌腱区分开来，并且可能起到沿肌肉力量产生轴动态调节刚度的作用。仅考虑纵向测量的应变可能会导致低估腱膜刚度及其弹性能量存储能力。
The elastic structures of many muscles include both an extramuscular free tendon as well as a sheet-like aponeurosis. An important distinguishing feature of aponeuroses is that these tendinous structures function as the attachment and insertion surfaces of muscle fascicles and therefore surround a substantial portion of the muscle belly. As a result, aponeuroses must expand both parallel (longitudinal) and perpendicular (transverse) to a muscle's line of action when contracting muscles bulge to maintain a constant volume. In this study, we use biplanar high-speed fluoroscopy to track the strain patterns of the turkey lateral gastrocnemius aponeurosis during active and passive force production in situ. We find that the behaviour of the aponeurosis during passive force production is consistent with uniaxial loading, as aponeuroses stretch only in the longitudinal direction. By contrast, our results show that aponeuroses are stretched in both longitudinal and transverse directions during active force production and that transverse strains are on average 4 times greater than longitudinal strains. Biaxial loading of aponeuroses appears to effectively modulate longitudinal stiffness, as we find the measured stiffness in the longitudinal direction varies in proportion to transverse strain. We conclude that biaxial strain during active force production distinguishes aponeuroses from free tendons and may function to dynamically modulate stiffness along the axis of muscle force production. It is likely that consideration of strains measured only in the longitudinal direction result in an underestimation of aponeurosis stiffness as well as its capacity for elastic energy storage.